What is the recommended imaging evaluation for a patient with a suspected concussion, considering their clinical presentation, risk factors, and demographics?

Imaging Evaluation for Suspected Concussion

Routine neuroimaging is NOT recommended for uncomplicated concussion, as conventional CT and MRI are typically normal in concussive injury and contribute little to concussion evaluation and management. 1

When to Image: Clinical Decision Criteria

Obtain noncontrast head CT immediately if ANY of the following red flags are present:

• Glasgow Coma Scale score <15 at 2 hours post-injury 1, 2
• Suspected open or depressed skull fracture 1
• Worsening or severe headache 1, 2
• Repeated vomiting 1, 2
• Focal neurological deficits 3, 2, 4
• Seizure activity 3, 2
• Signs of basilar skull fracture 2
• Coagulopathy or anticoagulant use 2
• Age >60-65 years with any symptoms 2
• Dangerous mechanism of injury 2, 4
• Prolonged loss of consciousness 3
• Progressive neurological deterioration 3, 4

Imaging Modality Selection by Timing

Acute Phase (0-48 hours):

• CT without contrast is the test of choice for evaluating intracranial hemorrhage (subdural, epidural, intracerebral, or subarachnoid) and skull fractures in the first 24-48 hours after injury 1, 4
• CT is faster, more cost-effective, and easier to perform than MRI, with high sensitivity for acute hemorrhage 1, 4
• MRI is inappropriate for initial evaluation when there is declining mental status or concern for acute hemorrhage, as it takes too long and patients are often too unstable 4

Subacute/Chronic Phase (≥48 hours):

• MRI is more appropriate if imaging is needed 48 hours or longer after injury, as it provides superior detection of cerebral contusion, petechial hemorrhage, and white matter injury compared to CT 1, 2
• MRI should be coordinated through the primary care or specialist physician evaluating the patient 1
• Advanced MRI modalities (gradient echo, diffusion tensor imaging) are better at detecting white matter alterations, especially in pediatric populations, though clinical utility remains limited by lack of research 1

Critical Management Points

If concussion is diagnosed without red flags requiring imaging:

• Remove patient from all physical activity immediately 3
• Perform thorough clinical assessment including detailed history of injury mechanism, prior concussions, symptom checklist, neurological examination with gait and balance testing (BESS, Romberg, tandem gait), and cognitive assessment 1, 3
• Monitor for deterioration over several hours 1
• Provide clear instructions on warning signs requiring emergency department return: worsening headache, repeated vomiting, increased sleepiness, abnormal behavior, or any neurological changes 1, 3

Common Pitfalls to Avoid

• Do not delay imaging when red flags are present while attempting "medical stabilization"—this can worsen outcomes 4
• Do not attribute declining consciousness to other causes (drugs, metabolic disorders) when clear trauma history with high-risk features exists 4
• Do not order routine imaging for uncomplicated concussion—this exposes patients to unnecessary radiation and cost without clinical benefit 1, 5
• In pediatric patients, use validated clinical decision rules (such as PECARN criteria) to minimize radiation exposure while ensuring appropriate imaging when indicated 2

Special Populations

Children and adolescents may require more conservative management with lower threshold for specialist referral, though the same imaging criteria apply 1, 3

Patients with prior concussion history, mood disorders, learning disabilities, or migraines have more complicated presentations but do not require routine imaging unless red flags are present 5